Cell culture vessels such as flasks, dishes, slides, wells, culture tubes and the like are utilized in a number of biomedical diagnostics applications to test for the presence of microorganisms in test samples such as patient specimens from humans or other animals. Likewise, other types of reaction vessels similar in format but differing in surface characteristics to cell culture vessels are utilized for immunological, molecular and biochemical analysis of the same.
For example, microorganisms may be tested for to assist in the diagnosis of an infection. Some infectious diseases are distinctive enough to be identified clinically. Most pathogens, however, can cause a wide spectrum of clinical symptoms in humans, many of which are not unique to a particular pathogen. Therefore, it is often necessary to use microbiologic laboratory methods to identify the specific organism that is causing a disease.
One method used to detect the presence of a microorganism causing an infection is to isolate and culture in an artificial medium the microorganism causing the infection. Both the presence and number of microorganisms in a patient's specimen can assist in defining the cause of a disease. To use this process, a specimen from a patient is placed in a liquid, solid or semi-solid medium that permits the growth of selective microorganisms. The medium may also include inhibitory substances that prevent the growth of microorganisms in the medium, other than the microorganisms the maker of the medium has selected. If the microorganism is present in the patient's specimen, it will grow in the medium and its growth will be detected.
Another method that may be used to identify the presence of a microorganism is to expose a living cell line that is known to be susceptible to particular microorganisms to a test sample from a patient. If the microorganism is present in the patient's specimen, the cells may exhibit cytopathic effects induced by that microorganism, which may be detected and confirmed by a fluorescent labeled monoclonal antibody. Typically, with such a process a cell line is grown on a suitable surface such as a cover slip disposed in the Petri dish, dram vial, culture tube or other vessel. Alternatively, the cell culture may be grown directly on the surface of a suitable vessel. The cell culture is inoculated with a clinical test sample, and then some of these vessels may be centrifuged to quickly introduce the microorganism into the cells. Typically, the cell culture is then incubated for a period of time to grow the organism, whereby the presence or non-presence of the microorganism is later analyzed, typically through visual inspection using an optical reader such as a microscope.
In many cases, to grow or culture cells both a solid surface and a liquid medium are needed. The solid surface provides a location upon which the cells can adhere, and the solid support typically mimics the cell's natural environment in the tissue from which they were derived. Often, the flat surfaces of tissue-culture flasks, trays, Petri dishes, multi-well culture plates, and even the inside surfaces of large roller bottles make ideal support surfaces for growing cells.
The medium in which the cells are immersed is the cells' source of nutrients. It is an artificial environment similar enough to the cells' natural environment to permit their continued growth and proliferation. The basic formulas of culture media typically consist of water, salts and amino acids, to which supplements such as serum, antibiotics, or growth factors can be added.
Most cell culture vessels are typically not well suited for performing all tasks in a diagnostic process. For example, a culture tube or Petri dish is often suitable for inoculation and/or incubation; however, many such cell culture vessels are not well suited for centrifugation and/or analysis. In general, cell growth occurs best on a modified plastic surface, while analysis and other processing is best performed on a glass surface. Consequently, test samples often must be transported between various vessels during the diagnostic process. Moreover, with vessels such as dram vials, culture tubes or Petri dishes, each test sample must be handled individually, which can become cumbersome when working with numerous samples.
Multi-well culture plates may also be used in diagnostic testing. A multi-well plate has multiple wells formed into a two-dimensional array within which one or more cell lines are grown. Often, however, such multi-well plates are restrictive in that it is difficult to culture multiple cell lines in a single plate due to different culture times required for each type of cell line. Moreover, there is a possibility of cross-contamination between wells. Also, if one cell culture in a multi-well plate becomes contaminated or otherwise inoperative, typically the entire plate must be discarded.
It has also been found that centrifugation causes a number of concerns with many conventional cell culture vessels. Typically, such vessels must be relatively sturdy to withstand the forces that occur in centrifugation. Moreover, an adequate seal must be maintained during centrifugation to prevent loss of the cell culture and/or contamination of other cultures, or the laboratory environment.
Accordingly, it is desirable to maintain a tight seal with various cell culture vessels subjected to centrifugation. However, a tight seal on a vessel may induce an aerosol effect when the sealing member for the vessel is removed. It should be appreciated that whenever a sealing member is removed under a tight seal, a vacuum is temporarily induced in the vessel. When the vacuum is released after the sealing member is fully removed, viruses or other biological agents or contaminants may be released into the atmosphere due to the sudden pressure change in the vessel. Such agents may be dangerous to operators, and they may also cause contamination of nearby samples.
Another concern is the vaporization of certain harmful processing chemicals such methanol, ethanol, isopropanol, dimethyl suphoxide (DMSO), phenol, or chloroform. Consequently, great care must be taken in removing a sealing member from conventional cell culture vessels.
Another conventional cell culture vessel is a multi-well slide assembly such as the SonicSeal four well slide available from Nalge Nunc International, which includes multiple wells joined together and secured to a slide plate through a breakable ultrasonic weld. An opener may be used to remove the upper structure of the wells from the slide plate such that the cell cultures disposed on the slide plate may be analyzed. However, such assemblies are not designed for centrifugation and include no suitable manner of sealing each well during centrifugation. The loose-fitting lid provided with such assemblies is insufficient to tightly seal each well.
Such assemblies are typically welded together using a two-step ultrasonic welding process. The upper structure is provided with a thin flange with a triangular cross-section on a mating end thereof (commonly referred to as an energy director) that is melted during ultrasonic welding to weld the upper structure to the slide plate. In the first step, the upper structure is ultrasonically welded to a distance of approximately one half of the length of the energy director to energize the molecules therein. Then, in the second step, a stronger weld is formed between the upper structure and slide plate through limited additional ultrasonic welding that further energizes the molecules but does not cause the energy director to become completely fused--thereby providing the break-apart property of the slide. After bonding, about 88 percent of the energy director is used up, with the mating surface between the upper structure and slide being only about 0.015 inches wide, which is only about 88 percent of the width of the base of the energy director, and only about 34 percent of the thickness of the sidewalls of the upper structure. The resulting bond is air- and liquid-proof and has sufficiently high mechanical strength for culturing purposes. However, the bond tends to leak during and/or after exposure to centrifugation forces, and thus is not suited for use in a centrifuge.
Therefore, a significant need exists for improved tools and an enhanced manner of performing cell culturing, diagnosis and/or testing of biological test samples with greater efficiency, reliability and accuracy. Specifically, a need exists for tools that are particularly suited for multiple activities to minimize the effort, time and potential contamination concerns associated with transferring test samples, cell cultures and the like between vessels.